Kilauea Caldera, Active volcanic caldera in Hawaii Volcanoes National Park, United States.

Kilauea Caldera is the main caldera of Kilauea volcano on the island of Hawaii, 4.7 km long, 3.1 km wide and 165 m deep, covering 10.7 km2 at an elevation of 1,222 m. Its floor is covered with lava flows, the oldest dating from 1885, and the pit-shaped Halemaʻumaʻu crater lies in its southwest. Crater Rim Road circles the depression past the Hawaiian Volcano Observatory and the national park visitor centre.

Kilauea Caldera began forming in stages 1,500 to 2,000 years ago, around the time Polynesians settled Hawaii, and grew through further collapses in the 16th and 18th centuries. Its floor is covered with lava flows, the oldest dating from 1885. Halemaʻumaʻu, the pit crater in the southwest, has hosted summit volcanic activity since 3 January 1983.

The name Kilauea was applied by Hawaiian residents to the summit area, while the pit crater within it was called Halemaʻumaʻu; the sources record that Polynesians who settled the island 1,500 to 2,000 years ago gave the latter a name but not the caldera itself. The name Halemaʻumaʻu refers to the home of the sacred ʻamaʻu fern. Offerings of lei and other gifts are still left at Halemaʻumaʻu, a practice tied to Pele, the volcano deity said to reside there.

The park provides marked viewing areas and safe pathways to explore the caldera, and checking current volcanic alerts before visiting helps with planning. Visitors should prepare for changing conditions since volcanic activity can affect access to certain zones.

Scientists monitor this caldera continuously, constantly recording data about earthquakes and gas emissions from underground. This intense observation makes it one of the most studied volcanic systems on Earth.